The invention relates to a method for transmitting and receiving signals between at least one first transmitting and receiving device and at least one further transmitting and receiving device, in particular for unlocking and/or locking a vehicle, as well as to transmitting and receiving devices and an arrangement comprising such devices for this purpose.
Methods such as these as well as transmitting and receiving devices are used, for example, in vehicle technology in order to allow the vehicle or the vehicle doors to be unlocked and/or the antitheft device to be deactivated in a manner which is as convenient as possible for an operator.
Passive access systems are being increasingly used for this purpose, in which an operator carries an ID transmitter with him which, in contrast to active systems, need not be operated by means of a button or the like, but communicates automatically with a corresponding base station which is located in the vehicle, as soon as the distance between the ID transmitter and the vehicle or the base station falls below a specific value.
Active and, in particular, passive, electronic key-operated systems such as these, which are generally based on the use of radio, are subject to stringent security requirements with regard to unauthorized access, with a power consumption which is as low as possible generally being desirable, since the power sources for the ID transmitter and/or base station are generally autonomous, in order to ensure operation even over a lengthy time period.